The long-term objective of proposed research is to identify and characterize those steps in viral RNA metabolism at which virus expression in cytomegalovirus (CMV) infected cells is regulated. The research plan is designed to investigate regulation at primary transcription and during post-transcriptional processing. First the events occurring during virus replication will be characterized with respect to the kinetics of viral and cellular DNA, RNA and protein synthesis. To investigate temporal control of primary transcription nuclear RNA extracted at appropriate times will be analyzed by liquid DNA/RNA hybridization with RNA in excess to determine the extent of genome transcribed. Similar analysis will be conducted in the presence of and after the removal of phosphonacetic acid. An analysis of symmetric transcripts will be pursued if viral RNA is found to be homologous to greater than 50% of the CMV genome. Experiments will be conducted to identify the origin of the DNA dependent RNA polymerase(s) responsible for transcribing the viral DNA. The extent of the viral genome transcribed in the presence of alpha-amanitin, cyclohexamide and rifampin (separately and at appropriate times) will be examined. If the data indicates the presence of a viral coded polymerase, attempts will be made to isolate ts mutants defective in the transcription of certain regions of the viral genome. To detect post-transcriptional regulation viral RNA sequences found in polyribosomes will be compared to those present in the nucleus. Polyadenylation and preferential translation of viral RNA transcripts will be investigated.